DESCRIPTION (provided by candidate): [unreadable] One of the basic tenants of Neurosurgical planning is the ability to generate an operative approach that minimizes the disruption of normal tissue while allowing the required exposure to target tissues. This tenet is pushed to an extreme when dealing with pediatric neurosurgical patients. To aid the surgeon in his or her ability to appreciate the location of target tissues as well as their relationship to normal tissues, graphical workstations have been developed. Such systems allow a surgeon to appreciate the position of the target tissues in relation to other normal tissues. The optimization of a surgical trajectory and the ability to guide a surgeon along that optimized trajectory has been the cornerstone of minimally invasive neurosurgical techniques. In order to register the real patient to the 3 dimensional computer model rigid fixation and dynamic referencing is usually required. These references are usually some form of cranial or spinal clamping system. For the pediatric population these devices are inappropriate. In our parent grant we proposed a new guidance system that utilized the design and fabrication of custom patient specific frames. [unreadable] These new frames are designed to mechanically register to the patient's anatomy and provide the required registration between the 3 dimensional model and the patient through surface fitting. The surgical trajectory is incorporated into the guide eliminating frames and operative tracking devices. These guides are fabricated using rapid prototyping technology. The development and testing of computer algorithms to enable this approach is the goal of the parent grant. Cranial and spinal procedures can now be planned and custom frames fabricated and brought to surgery. The design criteria for pediatric patients are, however, very different from that of adult patients. Every aspect of the procedure from imaging through operative positioning must be examined and optimized for the pediatric population. This proposal addresses the extension of this new technology, with the goal optimizing a system for pediatric neurosurgery. [unreadable] [unreadable]